Weight control and treatments for obesity have been the subjects of a large amount of suggested diets, treatments and procedures, including, in the most severe cases of morbid obesity, device implantations and/or direct surgical interventions. Recent comprehensive statistics from the National Institutes of Health (USA) indicates that more that 40% of Americans are obese, with more than 20% of these individuals being morbidly obese. In addition, it can be estimated that at least twice as many people are seeking to control their body weight, and/or are adhering to diets or other weight-control mechanisms. This is particularly significant since obesity has been implicated as a leading cause of various clinical conditions, including cardiovascular diseases and diabetes.
Six major streams of research and development related to new treatments for obesity are currently available: (1) diet regimens, and diet-related supplements and treatments; (2) pharmacological treatment using specifically developed medications; (3) gastric stimulation using implantable electronic devices; (4) invasive surgical procedures related to gastric reduction; (5) intragastric balloons or bezoars for reducing gastric volume and introducing a sensation of satiety and fullness; and (6) oral administration of cellulose or polymeric-based substances, which expand in the stomach and preclude their expulsion through the pylorus with the process of natural gastric peristalsis, thus introducing sensation of fullness and satiety. These expanded polymeric substances subsequently disintegrate chemically to allow for their expulsion from the body with natural gastrointestinal peristalsis.
Currently, there are very large numbers of various diets, diet supplements, diet regimens, and combinations thereof, and their numbers are growing dramatically. However, in many cases, these weight loss strategies do not work, or their success is very limited. The success of these techniques often varies widely between individuals, and they are often not sustainable.
Weight-loss related pharmacological treatment based on specifically developed and clinically-tested drugs and/or health supplements has also not been very successful. Numerous such therapies have been associated with various side effects, some of which are quite serious and life-threatening. Therefore, commercially-available and clinically-proven diets and/or anti-obesity drugs and health supplements have yet to be developed.
Recently developed techniques for gastric stimulation (see for examples U.S. Pat. Nos. 6,684,104, 6,615,084, 6,606,523, 6,600,953, 6,542,776, 6,535,764, and 6,449,511), involving surgical implantation of miniature microelectronic devices have been proposed as an avenue to tackle more severe cases of obesity, and particularly morbid obesity. The devices can administer electrical signals to the stomach and adversely affect normal propulsive gastric peristalsis. However, the procedures used for the positioning of the stimulating electrodes as well as the implantation of the device remain invasive, and the long-term effect of the treatment remains unknown both in terms of sustainability and safety.
Surgical procedures related to gastric volume reduction have been proven to be effective. However, they are invasive measures to address the problem of obesity. Mortality rates of procedures like gastric bypass or direct gastric volume reduction can reach 2%, have prolonged recovery periods, and can be quite expensive.
Bezoars are volume-taking phenomena occurring in the gastrointestinal tract of mammals, which are usually formed after systematic ingestion of hair (trichobezoars), some fruits or vegetables of high and specific fiber content such as persimmons (phytobezoars) or as a result of ingestion of substances and objects that cannot easily pass through the sphincters of the gastrointestinal tract (pica). Bezoars formed in the stomach and/or the intestines have been known to induce early satiety, anemia, and in extreme cases nausea, vomiting, bloating and gastro-intestinal obstruction (Charalabopoulos K et al., Phyto- and trichobezoars as foreign bodies in the gastrointestinal tract, International Journal of Clinical Practice, pp. 1741-42, 2006). Intragastric balloons positioned in the stomach either surgically or endoscopically to reduce the effective gastric volume mimic such bezoars and have been found effective in inducing early satiety and sensation of fullness, thus contributing to reduced food intake, which has been reliably related to sustainable weight loss (see for example U.S. Pat. Nos. 4,739,758, 4,485,805, 4,899,747, 5,234,454, 5,993,473, and 6,579,301). More recently, wireless control of volume-controlling devices in the stomach has been suggested (see for example U.S. Pat. Nos. 6,461,293, 6,454,699, 6,453,907, 6,460,543, and 6,450,946). Most recently, a “bow-tie” or “butterfly” intragastric bezoar has been suggested (WO/2006/122019, US Application 20060155311, U.S. Pat. No. 7,066,945) in contrast with the balloon shape proposed previously. The latter is launched endoscopically in the stomach and it is subsequently removed also invasively.
Although some of these techniques have shown to be effective in addressing the problem of obesity through intermittent gastric volume reduction from inside of the stomach thus avoiding surgical modification of gastrointestinal anatomy, they remain invasive and can be associated with serious and sometimes life-threatening side effects. The bezoars are positioned and removed invasively (in most cases endoscopically), and, more importantly, are built from non-permeable, impervious materials, and thus they are not permeable to liquids and gases, and are not disintegratable within the gastrointestinal tract. Therefore, they can potentially create life-threatening obstructions in the intestines, if they accidentally deflate, reduce volume or otherwise malfunction in the stomach and exit through the pylorus. These devices are not autonomously expandable, they are not of dynamically-manipulatable volume, and are not disintegratable from within the gastric lumen. Therefore, they are positionable and, most importantly, removable invasively (predominantly endoscopically), which limits the number that can be simultaneously present in the stomach. In addition, the lack of control over the dimensions of these bezoars triggers numerous other side effects in substantial number of patients, including vomiting, hypokalemia, abdominal pain, functional renal pain, gastroesophageal reflux, etc.
Most recently, the use of swellable polymers has been proposed to facilitate the reduction of gastric volume for treating obesity (see for example U.S. Pat. Nos. 5,750,585, 6,271,278, German Pat. No. NDN-050003290517, U.S. Patent Application No. 20040192582, U.S. Patent Application No. 20060020278). Compressed cellulose derivatives, or dehydrated hydrophilic polymers are introduced orally in the stomach, and expand to the point of not being able to pass through the pylorus, thus effectively achieving non-invasively what an intragastric balloon or another gastric volume-reducing device would achieve. However, in some instances, improper decomposition and/or degradation may lead to serious complications such as small bowel obstructions.
There is still a need for non-invasive techniques or products that can be easily used for prolonged and controlled reduction of gastric volume for use in facilitating weight loss, which address some of the problems encountered in the prior art. Our previous patent applications PCT/CA2007/000512 and PCT/CA2005/001693 offer some bezoar-based solutions to these problems. However, the bezoars discussed in these applications are multi-component, and are pre-formed. The aim of the present invention is to offer bezoar-forming units that can be utilized to form at least one volume-taking, permeable, temporary bezoar inside a given gastrointestinal organ, emulating the formation of trichobezoars and/or phytobezoars in mammals.